—We present a model that explains immunological memory as a consequence of the recursive proliferation of reactive and suppressive cells, where the relative proportion of these cells will set a probability for the emergence of a response (inflammation). We show that the underlying principle of the proposed model is a special case of P´olya’s urn process. This insight reveals and explains the emergent functionality of the model. Additionally, experiments and simulations are performed to validate the obtained insight of the model.